This is a comprehensive mod that adds a playable pony race (by means of polymorph spells), summons, companions, spells, mounts, and a couple of optional bosses. It is based on this mod by zdzichorowerzysta:http://www.nexusmods.com/skyrim/mods/6436/?

He rigged the model to work in Skyrim, then I was able to fix the crash to desktop problem with it and got his permission to use it and added the rest over time in creation kit. More detailed information is on the nexus/steam download pages.

I am hoping to make a similar mod for Fallout 4 but have not yet been successful in importing and rigging an animated model. I am trying using the dog skeleton/animations but no luck yet. I have no formal training in this, only a couple hundred hours fooling around in 3dsmax and nifskope, and don't know how to properly skin, weight, and rig.

It is unfortunate that the nif files for fallout 4 appear to be so much different from past nif versions. Its a bit of a surprise that they are using nif files at all since I assume they are no longer using gamebyro. I mean they might be. You just never know.

The good news though is that I recall seeing a few mods for fallout 4 that let you play as creatures. I think it was a cat actually. So it is actually possible